need help please with 36 gallon tank

Hi I have a new 36 gallon tank with a penguin 200 filter with biowheel which is cycling. Tonight I just noticed this grayish stuff klinging to the bottom of the filter tube that sits in the tank water. Not sure if this is good bacteria starting to grow or something else. I didn't want to wipe it off of the bottom of the filter tube if it is something beneficial for the tank water. The tank has been set up and going since Sat and I added fish on Monday. The water is fine nice and clear I have artificial plants in the tank and some decorations. What could this gray stuff be have heard it could be algae but am not sure my other tanks don't have it. Please help if you can I don't see this stuff anywhere else but on the end of the filter tube. Thanks any help is appreciated. Platytetrafan:help:

I could try to post a pick how do you post attachment?

Thanks so much I did clean it off Mgamer. Whatever it was just looked like sludge could have been fish poop who knows lol but it is gone now so am just keeping my eye on the tank. I will try to post pics am so happy I got the 36 gallon it looks so awesome and the fish love that shipwreck decoration I got they keep swimming around it I think they like the bubbles it creates. Will try to post pics soon.